Holy Cross Day commemorates the Cross of Christ as the instrument of salvation — not a symbol of defeat but of triumph. The feast originates in the dedication of the Church of the Holy Sepulchre in Jerusalem (September 13-14, 335), when the relic of the True Cross was venerated publicly. The September 14 date became the annual commemoration of this veneration. The feast proclaims the paradox at the heart of Christianity: what the world sees as shame and weakness, God reveals as glory and power.

The Helena legend — that she discovered the True Cross buried beneath a pagan temple in Jerusalem, identifying it through a healing miracle — is the defining tradition of this feast. Its absence from Eusebius, who described Helena's pilgrimage in detail but mentioned no Cross discovery, is a significant gap. Ambrose (395) is the first to attest it; by the fifth century, it was universally accepted. The three-crosses-and-a-miracle-test element appears in Rufinus but not in Ambrose — suggesting accretion over time.

The veneration of the Cross on September 14 was a major Jerusalem liturgical event, described by later pilgrimage accounts. The cross relic was displayed for public veneration, and fragments were distributed across Christendom — Cyril of Jerusalem (c. 348) already notes that pieces of the Cross had spread throughout the world. The Heraclius recovery (630) added a triumphalist dimension: the Cross rescued from pagan captivity and restored to its rightful place.

The feast's origins are tied to two historical events. First, the dedication of Constantine's Church of the Holy Sepulchre on September 13, 335, with the veneration of the Cross on September 14 — this is attested by Eusebius and early Jerusalem liturgical practice. Second, the tradition that Helena, Constantine's mother, discovered the True Cross during her pilgrimage to Jerusalem (c. 326-328).

The Helena legend does not appear in Eusebius — a significant silence, since Eusebius was both a contemporary and a court historian who described Helena's pilgrimage in his Life of Constantine. The discovery tradition first appears in Ambrose (De Obitu Theodosii, 395), Rufinus (Church History, c. 402), and subsequently in Socrates Scholasticus and Theodoret. The story of testing three crosses on a sick woman (or a corpse) to identify the True Cross appears in Rufinus and later sources but not in the earliest attestation.

• Commemorated